GDevelop TS typings for extensions

[malec-palec]

Hello there,

As a developer, I want to develop GDevelop extensions using TypeScript.
To be precise this kind of extensions - https://github.com/GDevelopApp/GDevelop-extensions

This requires GDevelop typings to compile a working project in strict mode.
As far as I know, there is no such thing at the moment.

Is there an existing way to generate a single index or a bunch of *.d.ts files from GDevelop sources?

If so, do you have any plans to distribute them as a separate npm package or as a part of the DefinitelyTyped project (e.g. @types/gdevelop package)?

[4ian]

Hi!

There are two kind of typings you may want to be interested in:

• The typings for the GDevelop "core" classes (the ones written in C++, representing a project and the tools to manipulate it, for example transpile it to a game, and their JavaScript version compiled with Emscripten). For these, TS typings are available here: https://github.com/4ian/GDevelop/blob/master/GDevelop.js/types.d.ts (and autogenerated, so always up to date with the C++ classes :)). This is useful when working on scripts or tooling manipulating games. Note that GDevelop-extensions and other repositories still don't take advantage of it but it's a matter of time before we do something so that this types.d.ts file is used.
• The typing for the game engine. Documentation is available here and generated from the TS sources and types.
  • Autocompletion is provided inside the editor, desktop version only. It works by feeding the raw TS sources to the integrated code editor.
  • We could ask TS to generate a .d.ts file for it, though it would add multiple seconds of codegen any time a change is made to the game engine (we use esbuild to build the game engine, which does its job in <1 second usually).

Could you precise a bit more what you have in mind? Do you want to build a full TS extension? Have you tried to build it from the editor?
Note that building something fully in JS in the editor is not for now super convenient because you need to rely on JavaScript (that you can type with JSDoc). We wrote some documentation here: https://wiki.gdevelop.io/gdevelop5/events/js-code/javascript-in-extensions/#embed-javascript-libraries-in-extensions

I guess we could improve this by:

• Enabling some part of an extension to be fully written in JS (instead of requiring to use the visual events)
• Better, embed esbuild so part or all of an extension could be fully written in TS

[arthuro555]

Generating type definitions for the Runtime is pretty easy using the typescript compiler. I've generated some (last updated for v185) for THNK, you can get them here.

You can generally check out the THNK repo as an example of an extension made in typescript: I have a compilation pipeline setup so esbuild will build & minify my typescript code, and insert it into the extension. Right now, I make the GDevelop functions that call the JS functions by hand (and just use GDevelop events in a few of them where it makes sense), but it wouldn't be much work to generate those bindings from a simple JSON/WebIDL/Whatever file

Publishing these types to DefinitelyTyped would be a bad idea, since that is not what that project is for - it is meant as a way for the community to create typings for existing npm packages that lack these and the maintainer of said npm package won't do it themselves, to make usage of js packages in typescript possible.

[malec-palec]

@4ian, thanks for the clarification. I was looking for the game engine's typings.

While I was preparing a minimal usage sample, @arthuro555 pointed out what I needed:

I've generated some (last updated for v185) for THNK

and described pretty much my use case:

... an extension made in typescript: I have a compilation pipeline setup so esbuild will build & minify my typescript code, and insert it into the extension.

I have the same goal, only the implementation is different.

@arthuro555, how do you generate arthuro555/THNK/types?
Can you share a script for this?

After that, the remaining questions are:
how to make these types available globally via npm and synchronize with the exact GDevelop version - for every released editor version (even beta) should be a matching types version.

[arthuro555]

how to make these types available globally via npm and synchronize with the exact GDevelop version - for every released editor version (even beta) should be a matching types version.

This is just not necessary? Why bother, when just copying the typings folder into your project is enough.

how do you generate arthuro555/THNK/types?
Can you share a script for this?

I do not have a script for this and always do it manually, since it is pretty easy and standard usage of tsc to output dts files.
I rarely ever need to update them too: GDevelop's APIs are stable, and when a change is necessary a new one is added and the old one stays untouched. New APIs are niche and rarely useful in an extension. I hadn't had the need to update them for years before v185 (where I needed the new scene loading APIs).

[malec-palec]

This is just not necessary? Why bother, when just copying the typings folder into your project is enough.

Folders сopying doesn't work well with CI/CD pipeline. Especially when you are outside of a single monorepo. And want to return to some fixed version back in time.
I'd like to have TS extension in the form of npm package with dev dependency to game engine types and the ability to fix its version by semver rules.

I do not have a script for this and always do it manually, since it is pretty easy and standard usage of tsc to output dts files.

Let's get practical. Here is a simple example master...malec-palec:GDevelop:chore/typings
I've got 20 errors when executing npm run postbuild command in ./GDJS folder. What do I do wrong?

Some types have dependencies (e.g. import("pixi.js")) whose types are outside ./GDJS/types folder, so you need to add them to devDependencies as well.

Also, types output has a bunch of files with an empty body inside gdjs namespace, types for tests have no real use.
As a nice addition, all types can be bundled into a single index.d.ts file.

New APIs are niche and rarely useful in an extension. I hadn't had the need to update them for years before v185 (where I needed the new scene loading APIs).

I'll have such a need in the near future, right after Spine extension is merged.
Let's stick to Semantic Versioning to track public API changes.

We could ask TS to generate a .d.ts file for it, though it would add multiple seconds of codegen any time a change is made to the game engine (we use esbuild to build the game engine, which does its job in <1 second usually).

Or it can be a separate script for generating and publishing types which should be called once during the editor's release routine.

@4ian, what do you think about that?